Epicyclic double-reduction transmission



EPICYCLIC DOBLE REDUCTION TRANSMISSION Filed June 25, 1926 CII Patented Mar. 19, 1929..

UNITED STATES PATENT OFFICE.

GEORGE SMITHZ MORISON, OF PITTSBURGH` PENNSYLVANIA, ASSIGNOR TO MORISON INCORPORATED, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF DELA- WARE.

Application led June 23, 1926.

This invent-ion relates to power transmission devices; more particularly to a gearless transmission adapted to effect great reduction in Vthe speeds of relatively movable machine element-s or the like.

It is among theobjects of this invention to provide a power transmission device which is adapted to eect a relatively great reduction of speedsbetween a driving and a driven element in which the driving and driven members are journaled for rotation in coaxial alignmeiitand in which that-ransmutation elements comprise a minimum number of simple correlated parts, compactlyhoused in a unitary casing member, and arranged to constitute a comparatively quiet, mechanically etlicient, durable, and compact power transmission unit'.

Another object of this invention is to utilize' in a power transmission device a plurality of rolling members cooperating with an eccentrically driven and driving thrust member and surrounding corrugated races, the thrust member-having an epicyclic movement relative to the surrounding corrugated races, the parts being so proportioned and arranged thatthe rolling'members shall at all times be in contact with the circular thrust member and` cooperating corrugated races. Y

ln laccordance with the present invention a great reduction of speed oi' Yspeed ratio is effected by utilizing two series orA groups of roller members coopera-ting respectively with twocorrugate'd races and a single epivcyclically moving thrust member in the manner-hereinafter set forth. Y

`In the accompanying drawing constituting a part hereof, and in which like reference characters designate like-parts, Fig. 1 is a. view partially in section and partially in elevation of a transmission device embodying the principles of my invention; and Fig..2 is a similar view taken along the line II-H, Fig. 1. Y

Referring to the several ligures of the drawings, the structure therein illustrated comprises a casingV 1 provided with a journal bearing 2 for rotatably journaling a `shaft member 3 which constitutes the driven element of the power transmission device. An end brackett having an off-set portion 5 adapted to seat on a complementary shaped portion of the housing 1 is secured EPICYCLIC DOUBLE-REDUCTION TRANSMISSION.

Serial No. 117,963.

for receiving two groups or series of rollersA 12 and 13. The two series of rollers are divided into separate groups by the off-set portions for a purpose hereinafter stated. rlhe several rollers of each group are of the same dimensions, and preferably those of the two groups are also identical. That makes them interchangeable and simplifies the proportioning of other parts.

The cage member 9 is provided with a central recess 14 for receiving an anti-friction or ball bearing member 15 which journals a shaft 1G' at a restricted eiid portion 17 thereof, and the shaftmember 1G is further rotatably journaled through an air-tight packing 18 provided in the bracket member et. and a. plurality of rollers 20, 20 and 20a. The shaft 16 is in coaxial alignment with the shaft 3 and in the operation herein described constitutes tlie driving member of the transmission device. i

A cage member 19 comprising a pair of disks 19a carries the rollers 20, 20, 20, in

suitable bearing pads 21 attached thereto.

rlhe disks 19 are joined by rivets or rods 22 to retain the rollers 20, 20, 20a in their relative positions as shown in Fig. 2. These roller members are of different sizes, the two similar upper members 20, 20, as shown in Fig. 2 being larger in diameter than the lower member 20a, whereby the rollers cooperate with an outer eccentrically mounted rotatable race 23 to produce a wedge action vbetween the rollers, the shaft member 16,

and the race 23. By this arrangement member 23 operates as a driven and driving thrust ring having eccentric rotative movement relative to the axis of rotation of the shaft 1G.

Although the members 12, 13, 2O and 20a are shown herein as spherical in shape, the broad termi'ollers is used for all of them for the reason that their function is merely to act as rollers between the races with which they Contact inside and outside, and other forms of rollers may be used, as for An outer race 26, provided with corruga tions 30 (Fig. 2), is secured to the bracket e in a fixed position, and the shaft member 3 Vis provided with a similar corrugated race 27 which is formed by an integral extension 29 of the shaft or otherwise associated there with in any suitable manner so as to be rotatable with the shaft and by the means described. f

The corrugations of the races 26 and 27 vare in the form of arcs of circles the radii of whichv equal the diameter of the roller members 12 and 13 with which they cooperate, respectively. rThe number of corrugations V,in the races 26 and 27, and the" number of rollers 12 and 13 in the respective groups may be varied, subject to certain mathematical limitations, in accordance with the speed'ratio it is desired to obtain.

.In operation, the drive shaft 16 is tie high yspeed element and may constitute the arma- ,Y tuie shaft of a motor, the drive shaftv of any l prime mover, or a` connection thereto.VV TheV rotation of the drive shaft rotates the ball or roller members 20, 20, 20, which,by vir-- tue of their engagement also with the thrust ring 23, tend to rotate and revolve the latter in a direction opposite to the direction of rotation ofthe drive shaft'16. The thrust ring 23, by virtue of its eccentric epicyclic movement, progressively pushes the circular members 12 and 13 into the corrugations of the races 2 6 and 27, respectively. Since the race 26 is fixed or stationary it acts as a fulcruin for thel roller members 13 as they are driven down the inclined faces of the corrugations of the race 26under prese sure of the thrust of race25. The effect by i drive shaft I tary members 20, 20, 20a. the cage carrying rollers 20, 20, 20, is how-k reaction of the rolling members 13 on the fixed surface of race 26, is a driving rotative movement of thecage member 9 in which 'they are carried, therotation of the cage being in'opposite direction to that of the rollersy 13 but in the direction of travel of the rollers 13 as a whole.

"'Tlie speed of rotation of the thrust ring 23 is governed by the speed of rotation and rolling motion of the rollers 13 as they travel on the slopes ofthe corrugations of the race 26. The cage member retaining the rollers 20,-20, 20, is fr ee torotate'and it tends to rotate'in the direction of rotation of the 16', driven' by the roller plane- This tendency of ever, dependentyon rotation of the race 23, since if that member be held against any rotation whatever the cage will necessarily be rotated at a speed determined entirely by peripheral speed of theshaft 16 andthe rollers 20,20, 20a. AOn the other hand if the race 23 be free to rotate the cage may stand still,-rotatien ofthe shaft 16 being translated through rotation of rollers 20, 20, 20L on fixed axes into rotation of race member 23. Any variation in comparative speeds of rotationbetween the two extreme conditions of Zerofor either as Vjust'stated may be obtained by wholly or partly restricting the rotation of one while leaving the other freeto rotate. Therefore, in the present case, since the cage carrying the rollers 20, 20, 20il is freely mounted and can' therefore be considered as a floating meinber, adJusting its speed of rotation as required by the speed of rotation, or even non- Hrotation ofrace memberv23, the latter may be'a'nd is controlled by external resistance. Consequently the race member 23 is directly governed in respect to speed of rotation by reaction on it of rollers 13 as they are forced to roll down the inclined faces of the corrugated race 26 bythe progressive or epicyclic thrust resulting from the eccentric movement of the ringv 23 by virtue of revolution of the unequally sized rollers 20, 20, 'between that ringand the shaft 16.

The number of corrugations 32 in the race 27 is less than the number of similar corrugations 30 in th'e'race 26, and the number of rollers 12 is one less than the number of corrugations 32. The successive corrugations of the races 27 andA 26 will therefore necessarily Ybe out of alignment in relative radial position, as shown in Fig. 2. Aiccordingly when lthe rollers 13 cooperating with therace 26 are driven downwardly into the lower portions between the Vvcorrugations 30of that race,the next adjaccntk'or corresponding rollers 12 ofthe other 'group cooperating withfthe corrugatioi'is 32 of the race 27 willdrive the movable race27 a slight distance. in order to compensate for the differencein position of the rollers that would otherwise result, producing'a lcreepage of the rotatable member 27. in a direction opposite to thedirection of rotation Vof the cage member 9. l Since the race member 27 constitutes an integral part of the driven shaft 3, the amount 'of creepage governs the speed of rotation of the' driven shaft 3, which will be relatively very small as com-v pared to the speed of iotationrrofy the drive shaft 16. v`

'The eccentrically driven rotatable thrust ring 23, the rollers 13 Vand the corrugated race 26, are in thenature of Van epicyclic gear cooperating .vith: anouter raclr- Such arrangements produce a reductionv of speeds much as does'the commonly termed wabblc lil) gear drive. rlhus where there are nineteen rollers 13 cooperating with a race 26 having twenty corrugations, the retaining cage 9 will make one complete rotation for nineteen revolutions of the cage i9 cooperating with the thrust ring 23 which is effective in pushing or forcing the balls against the corrugations.

lf the number and size ot' corrngations et the races 2G and 27 were the same and t-he series ot' rollers vl2 and 13 were equal in num beil and vsize there would be no resultantdisplacement or creepage of the movable race Q8. The greatest reduction in speed between the driven cage 9 and the driven element 3, ot' which the race 27 constitutes an integral part, is effected by the least difference in number of corrugations on the respective races 26 and 27.

By making the radii of the corrugations equal to the diameter of the rollers, a substantially constant contact between the rollers and corrugated paths ot' the races is secured. This lessens the wear and noise in operation and also lessens the strain on all bearings.

A transmission device made in accordance with this specification provides a simpleY and compact apparatus for effecting an enormous reduction in speed of relatively movable parts, with elimination of gear teeth, and with apparatus that maybe manufactured at well equipped machine shop, in cooperation y'ith rollers of standard sizes that are universally available.

I claim:

l. In a powerV transmission device, the combination with a driving and a driven element ofl a plurality offroller retaining cage members, series of rollers respectively carried by said cage members, a double roller race disposed around oneseries o'l said rollers Yand cooperatively engaged with all of said rollers, a tulcrum Vmember for engagement with one series ot said rollers, and

`means for effecting driving engagement of another series of said `rollers with vsaid driven element.

2. In a power transmission device, combination with a driving and a driven element '01"' a plurality of roller retaining cage members, series of rollers carried by said members, al double roller race disposed arrnmd one series of rollers and cooperatively engaged with all of said series of rollers, a-'tulcrum member for engagement with one of said series of rollers, and a roller engaging member associated in iixed relation with said drivenelement for driving engagement with another series of said balls or rollers.

5. ln a power transmission device, the combination with a' driving and a driven element journalled tor rotation in coaxial alignment,or` a plurality oi roller retainthe ing cage members mounted concentrically with said elements, series of rollers carried respectively by said cage members, a race member disposed between and in engagement with said series ot' rollers, a corrut gated race fixed to constitute a fulcrum for one series olz rollers, and a second corrugated race rotatable with said driven element and adapted to be driven by engagement with one of said series ot' rollers.

4.111 a power transmission device, the combination with a. driving and a driven element journalled tor rot-ation in coaxial alignment, of ay plurality ot roller retaining cage members mounted concentrically with said elements, series ot rollers carried by said cage members, a race member constituting a thrust ring disposed between and in engagement with said series of rollers and adapted for eccentric movement relative to the axes ot said driving and driven elements, a corrugated race fixed to constituteI a tulcrum for one of said series of rollers, and a corrugated race rotatable with said driven element adapted for driven engagement with another ot' said series ot' rollers.

5. In a power transmission device, the combination with a driving and a driven elcment journalled for rotation in coaxial alignment of two roller retaining cage members mounted concentrically with said elements, a series of rollers carried by the tirst of said cage members and adapted to constantly and operatively engage said driving element, two of said rollers having unequal diameters, rollers arranged in two unequal series in the other cage member, a thrust ring disposed around and adapted for engagement with the first mentioned series ot rollers and adapted to engage the two series of rollers of said second mentioned cage, a stationary corrugated race constituting a fulcrum for one ot said series of rollers in the second cage, `and a movable corrugated race adapted to be driven by engagement with the other of said series ot' rollers carried by the second cage member, said movable corrugated race being positively connected to the driven element.

6. In a power transmission device, the combination with a driving and a driven element et a plurality ot` roller retaining cage members, rollers carried by said cages and operatively engaged with said elements. and a corrugated race for one series oit said rollers in which the corrugations are bounded by arcs of equal circles the radii of which is equal to the diameters of the rollers with which they cooperate.

7. In a power transmission device, the combination with a driving and a driven element journalled for rotation in coaxial alignment, of a plurality of roller retaining cage members journalled concentrically therewith, `a roller race disposed interina lll() equal diate said cage members, a plurality oiE rollers carried by one of said cage members kand operatively engaged with said drive element and said race, two of said rollers having unequal diameters, a plurality ot rollers carried in groups by the other ot' said cage members, a stationary race in alignment with and adapted to engage one ot said groups otrollei's, and a racc rotatable with said driven element and in engagement ywith the other of said groups of rollers, said stationary and said last-named rotatable races being adapted to cooperate to eiliect rotation ot said driven element.

8. A power transmission device comprising'a ldrive shaft 'havinga fixed axis, a series of not less than three rollers circumferentiallyspaced apart on'and iii-contact.

`with the drive sli-att, two of said rollers having unequal diameters, Va ring member surrounding and in contact with said unl rollers, said ring member being adapted to be rotated and revolved by travel ot the unequal rollers onthe drive shatt, a large and -a small race on the exterior Vperiphery ot said ring, a cage member siii'- rouiiding the ring mounted coiicentrically with the drive shaft and having therein a large series and a small series ot spaced rollers adaptedto contact respectively with Y said large and smallrz ees on said ring member, a iixed outer race in cooperative alignment with said large race and having its operative face divided into corrugations, the

large 'series of rollers being positioned between and in Contact with said large race and said xed corrugated race, a concentri- Vcally mounted movable outer corrugated race inA operative alignment with said small race, the rollers of said small series` being positioned between and in contact with said small race and said movable corrugated` race, 'whereby to transmit rotation of the drive shaft'v to-rotation of the movable corrugated race withreduction of speed oti'otation.

9. "The combination ot elements recited in claim 8 further'characterized by the rollers ot the said small land large series being one less in number, respectively, than the number ot eoirugations in the outer movable race and the outer iix-ed lrace, respectively.

10. The combination ot elements recited in claim 8 tui-ther characterized by the fact that the corrugations ot the two outer races are bounded by arcs of equal circles the radii ot which are respectively equal to the diameters of thc rollers adapted to be in Contact therewith. Y i

11. The combination et, elements recitedv 12.7111y a power transmission device, the

to constantlyV and operatively engage Vsaid driving element, two of the said yrollers having unequal diameters, other rollers arranged in .two unequal series in different planes Vand carried in the said cage member,

athrust' ring positioned eccentrically with respect to the driving member disposed around and in engagement with Athe first mentioned series of rollers, and having a periphery comprising two circular faces ot diilerent diameters adapted respectively to engage theV two unequal series of other rollers, an outer stationary corrugated race constituting a tulcrum for one of said series of rollers carried by the cage, and a movable corrugated race adapted to be engaged and driven' by the other of said series ot rollers carried by the cage, said movable corrugated race beingV positively: connected to or constituting the driven element.

13. ln a power transmission device, the combination with a driving and a driven element Vmounted for coaxial rotation, of a rotatable roller-retaining cage member mounted coaxially with the driving member, an eccentrically positioned ring disposed inside said cage member, a plurality of inner rollers operatively engaging said driving element .and said ring, two of said inner rollers having unequal diameters,y aplurality ot equallysized outer rollers arranged in two unequal series in diiferent rplanes carried by and revoluble with the said'cage vmember andk engaging the exterior tace ci .with the other of said series of outer rollers and connected to or constituting the driven element, whereby.;- to transmit rotary motion ot the driving element to rotary motion of the driven element at a Vdifferent rate ot' rotation. r Y e 14, In a power vtransmission device, the combinationwith a rotary vdriving element of a seri-es of revoluble rollers mounted upon the driving element as a race, two of said rollers having unequal diameters, a ring having an inner and two unequal outer races, the inner race bearing upon and surrounding said rollers whereby the ring is eccentrically positioned with respect tothe driving element, a rotatable cage member surrounding and coaxial with the'driving element, two unequal series ot 'rollers held in andrei/oluble with the .cagejga-nd bearingrespectively on the two unequal outer racesY of said ring, a fixed corrugated iilcrum race outside ot and.,ineontactwith` oneV ofy said series ot caged rollers, and a rotatably mounted corrugated race outside of and in Contact with the other series of rollers in said cage and adapted to be driven thereby.

15. The combination of claim 14, .the rollers of the two series in said cage being respectively of diameter equal to the radius of the corrugationsin said outer races.

16. The combination of claim 14, the number of rollers in one outer series being one less than in the other outer series.

17. In a power transmission device the combination of an eccentrically driven rota-tably and revolubly mounted ring member vhaving two unequally sized circular tracks on its outer periphery, a cage member rotatably mounted on a fixed axis and surrounding the eccentric member, a series vof rollers mounted in the cage revoluble therewith free to' move in radial relation thereto and in contact with one oi the tracks on the eccentric member, a second series of rollers similarly mounted in the cage and seated upon the other track of the eccentric member, corrugated races surrounding and in contact with said series ot rollers, one of said corrugatedv races being lifted, the other corrugatedV race being rotatably mounted and coaxial With said cage member, whereby to drive the movable corrugated member.

18. In a power transmission device the combination of an eccentrically driven rotatable and revoluble member having two unequally sized circular tracks on its outer periphery, a cage member rotatably mounted on a fixed axis and surrounding the eccentric member, the axis of revolution of the eccentric member and of rotation of the cage member being the same, a series of rollers mounted in the cage revoluble therewith tree to move in radial relation thereto and in contact with one of the tracks on the eccentric member, a second series of rollers similarly mounted in the cage and seated upon the other track of the eccentric member, all the said rollers having equal di ameters, two corrugated races surrounding and in contact with said series ot' rollers, the corrugation ot said races being equal arcs having a radius equal to the diameter of the rollers cooperating therewith, the number or" corrugations of each race being one greater than the number of rollers in the series of rollers bearing thereon, one of said corrugated races being lixed, the other corrugated race being rotatably mounted and adapted to be driven by the said rollers bearing thereon.

In testimony whereof, I sign my name.

GEORGE SMITH MORISON.

Cil 

